Shell chair construction

ABSTRACT

A shell chair construction comprising a shell of molded rigid polyurethane shaped to define seat and back portions in which the seat portion has applied to same a seat assembly comprising a contoured seat pan of plate like construction, to the upper side of which is applied seat padding covered by fabric material that is brought around the rim of the pan and stapled thereto on the underside of the pan. The pan carries spaced fastener elements made fast thereto for reception in correspondingly located holes in the shell seat portion to receive fastener screws that secure the seat subassembly and the chair iron in place on the chair shell. The shell includes compression inserts embedded in the shell portion through which the said shell seat portion holes are formed, and against which the seat pan is clamped by the fastener screws that make the seat assembly and chair iron fast to the chair shell. The seat pan defines a downturned marginal rim which is clamped against the shell seat portion by the action of the fastener screws, to clamp the seat padding covering fabric in place.

United States Patent [19] Harris et al.

[ SHELL CHAIR CONSTRUCTION [75] Inventors: Everett K. Harris, Geneva; William P. Anderson, North Aurora; James W. Lannert, Oswego, all of 111.

[73] Assignee: All-Steel lnc., Aurora, 111.

[22] Filed: July 23, 1973 [21] Appl. No.: 381,772

[52] US. Cl 297/455, 297/451, 297/458 Primary Examiner-Casmir A. Nunberg Attorney, Agent, or FirmMann,.Brown, McWilliams & Bradway [5 7 ABSTRACT A shell chair construction comprising a shell of molded rigid polyurethane shaped to define seat and back portions in which the seat portion has applied to same a seat assembly comprising a contoured seat pan of plate like construction, to the upper side of which is applied seat padding covered by fabric material that is brought around the rim of the pan and stapled thereto on the underside of the pan. The pan carries spaced fastener elements made fast thereto for reception in correspondingly located holes in the shell seat portion to receive fastener screws that secure the seat subassembly and the chair iron in place on the chair shell. The shell includes compression inserts embedded in the shell portion through which the said shell seat portion holes are formed, and against which the seat pan is clamped by the fastener screws that make the seat assembly and chair iron fast to the chair shell. The seat pan defines a downturned marginal rim which is clamped against the shell seat portion by the action of the fastener screws, to clamp the seat padding covering fabric in place.

6 Claims, 10 Drawing Figures PATENTEL DEC 74 SNEU 1 0f 4 PAIEMELHR 3,851,920 SHEEI 30? 4 PATENTELBEB 31914 335L920 SHEET u (If 4 SHELL CHAIR CONSTRUCTION This invention relates to a shell chair, and more particularly, to shell chairs of the type in which the chair body is in the form of a molded rigid plastic material that defines the basic configuration of the modern contour shell chair.

Chair bodies for chairs of this type are usually made by injecting a suitable plastic, such as a suitable polyurethane, into a mold that provides the basic chair body contours. The molded urethane becomes rigid for good shape holding characteristics, but this material does not resist localized stresses well, and it has become the practice to incorporate in the plastic seat body a seat board and the like to provide a means to secure the chair base to the body and secure covering fabrics in place.

The shaping and arrangement of the chair body seat portion in chairs of this type is rather critical as the chair arrangement involved must provide room for adequate cushion padding for user comfort, while insuring that the chair seat portion have the thin appearance that is desired for shell chairs of circumfluent design.

A principal object of the invention is to provide a seat arrangement for contour shell chairs which provides for secure but releasable securement of the seat to the shell in a manner that also accommodates securement of the chair iron to the shell. Another principal object of the invention is to provide a chair arrangement of the molded shell type that includes a readily removable seat subassembly of simplified form that is held in place by the same connectors which secure the chair iron to the shell. I

Other objects of the invention are to provide a chair arrangement of the molded shell type in which localized stresses on the rigid urethane material are avoided in securing the seat pad and chair iron to the shell, which permits refurbishing of the chair in the field, where desired, and which is economical of manufacture, attractive in appearance, and long lived in use.

In accordance with this invention, the chair comprises a molded shell formed from polyurethane, defining the usual shell seat and back portions, in which the shell seat portion has embedded in same a reinforcing seat board that underlies the upwardly facing surface of the seat portion and is exposed at the underportion of the shell to receive the chair iron, and a tack strip of generally Ushaped which is disposed around the inside margin of the seat portion, along the back and sides of same, for securement thereto of the fabric that covers the shell sides and back.

A seat subassembly is provided that comprises a contoured seat plate or pan having seat padding applied thereto on its upper side that iscovered by fabric material which has its edges brought around and anchored to the underside of the pan. The shell seat portion has embedded therein spaced compression inserts that bear on the seat board in which are formed fastener receiving openings that receive tubular fastener elements that are anchored to the seat pan, and that in turn receive securement screws to be applied to the underside of the shell seat portion to secure the seat subassembly and chair iron to the shell through its seat portion. The seat pan defines a downwardly angled rim portion that is clamped against the shell, by the securement of the chair iron and seat subassembly in place, to clamp the edges of the fabric that lie about the seat portion in place. This shaping of the pan rim portion permits the pan margin to accommodate any bunching of the turned over seat subassembly fabric material edging on the underside of the pan, and also provides a convenient place to staple the fabric of the seat subassembly to the pan.

Other objects, uses and advantages will be obvious or become apparent from a consideration of the following detailed description and the application drawings.

In the drawings:

FIG. 1 is a frontal perspective view of a completed chair in accordance with this invention;

FIG. 2 is a top plan view of the molded shell that defines the basic contours of the chair;

FIG. 3 is a vertical sectional view through the shell seat portion, showing the chair seat subassembly, the chair iron, and the shell padding applied thereto;

FIG. 4 is a fragmental cross-sectional view of the forward portion of the seat subassembly as applied to the shell, but on an enlarged scale to better illustrate details of construction;

FIG. 5 is a top plan view of the seat pan or plate that forms a part of the chair seat subassembly;

FIG. 6 is a front elevational view of the seat pan shown in FIG. 5;

FIGS. 7 and 8 are transverse cross-sectional views through the seat pan, taken substantially along lines 77 and 88 of FIG. 5, respectively;

FIG. 9 is an enlarged fragmental view illustrating the fastener and securing screw arrangement that is employed in connection with this invention; and

FIG. 10 is a fragmental cross-sectional view taken substantially along line l0l0.

However, it is to be understood that the specific drawing illustrations provided are supplied primarily to comply with the requirements of the Patent Laws, and that the invention is susceptible of other embodiments that will be obvious to those skilled in the art, which are intended to be covered by the appended claims.

GENERAL DESCRIPTION Reference numeral 10 of FIG. 1 generally indicates a shell chair arranged in accordance with this invention, which comprises a shell 12 (see FIGS. 2 and 3) of rigid polyurethane that is shaped to define seat portion 14 and back portion 16 and sides 18 and 20 that in the form shown are shaped to provide chair arms (though the presence or lack of chair arms is immaterial to the present invention).

i The chair shell seat portion between the sides and back of the shell defines an upwardly facing surface 22 having a generally flat or planar marginal portion 24 which is in circumambient relation about concave portion 25 which defines a socket like seat in which seat subassembly 26 is received.

The shell seat portion has embedded therein a seat board 28 (see FIG. 3) to which, in accordance with this invention, the seat subassembly 26 and chair iron 30 are secured to secure them to the shell 12. The exposed surfaces of the shell seat and back portions 14 and 16 and sides 18 and 20 are covered with soft padding 32, which is in turn covered by fabric finishing material 34. The seat portion 14 has embedded in same at or near the seat portion surface portion 24 a U-shaped tack strip 36, to which the fabric material 34 is stapled as at 38 about the back and sides of the surface portion 34,

with the fabric material 34 being stapled to the seat board as at 40 on the underside of the shell. The fabric material 34 covering the chair seat portion 14 at its forward edge 42 is secured along the surface portion 24 by stapling as indicated at 44.

In accordance with this invention, the shell seat portion has embedded therein in engagement with the seat board 28 on its upwardly facing side 46 a plurality of compression inserts 48 which have formed through same fastener receiving openings 50 that are aligned with'correspondingly located fastener receiving openings 52 of the seat board to receive the individual fastener devices 54 which secure the seat subassembly and chair iron to the shell.

The seat subassembly 26 comprises a seat pan or plate 56 (see FIGS. 8) which is of contoured configuration and of platelike construction and has applied to same padding 58 that is covered by fabric material 60 that has its marginal edge 62 turned around the rim 64 of the seat pad and secured thereto as by stapling at 66.

The fastener devices 54 comprise tubular internally threaded fastener elements 68 that are made fast to the seat pan 56 and project from the seat pan for application into the respective pairs of aligned openings 50 and 52, which are respectively formed in the shell I2 to form the respective fastener receiving openings 70, for application thereto of fastener screws 72 that secure the seat assembly 26 and chair iron 30 against the shell seat portion 14. Chair iron 30 is suitably secured to chair base 31 equipped with suitable casters 33.

Further in accordance with this invention, the seat pan 56 about its rim defines a downwardly angled rim portion 74 which is clamped against the shell seat portion surface portion 24 by the action of the fastener screws 72 in securing the seat assembly 26 and chair iron to the shell. the downwardly angled rim portion '74 thus acts to clamp between the seat pan and the chair shell the fabric edges that come between same to hold same against dislodgement, and also the shaping of the rim portion 74 defines a recess 76 (see FIG. 4), which accommodates the gathering of the fabric material 60 that occurs in applying it around the pan rim 64. Rim portion 74 also serves as a convenient location for the stapling 66.

SPECIFIC D ESCRIPTION The shell I2 may be formed from a suitable urethane material that is rigid when the molding procedure is completed, with such material being suitably shaped in a suitable mold to provide the shell type circumfluent configuration that is illustrated. Seat board 28, the compression inserts 48, and the tack strip 36 are molded in place in the positions indicated in the drawings, with the compression inserts being suitably initially secured to the seat board in any suitable manner, as by stapling. The seat board and inserts may be formed from plywood, a suitable particle board, or the like, cut to appropriate size, with the openings 50 and 52 being formed after the molding operation is completed by a suitable drilling procedure. As indicated in FIG. 3, the shell seat portion 14 is relatively thick in transverse dimension in the area of its surface portion 24 and the concave contour of surface portion 25 indents the upwardly facing surface 22 of same downwardly to provide a relatively thin transverse shell dimension at the mid portion of the seat. As indicated in FIG. 3, the seat portion is suitably indented as at 80 and 82 to expose the respective compression inserts 48.

The seat board 28 has its undersurface 47 exposed for application thereto of a cover member 84, that may be formed from cardboard or the like, that is suitably secured in place, as by employing stapling, to mask the edges of the fabric 34 that held in place by stapling 40. The chair iron 30 seats against the cover member 84.

The chair iron 30 is entirely conventional and as the usual practive, has secured thereto in any suitable man ner, the base 31 equipped with the casters 33 on which the chair I0 rests.

The seat portion 14 of chair i2 is also formed to define a plurality of spaced openings 84 that extend therc through and through seat board 28 for breathing purposes.

The tack strip 36 may be formed from untempered masonite and preferably is within 3/l6th inch of the surface portion 24.

The seat plate or pan 56 generally comprises a dished member formed to define the relatively flat marginal portion 92 which is in circumambient relation about dished portion 94 that is concavo-convex in configuration that is shaped to receive and contain the cushion padding 58. The dished portion 94 is downwardly indented as at 96 and 98, respectively, to mate with the respective indentations 80 and 82 of the shell seat portion. The indentations 96 and 98 are each formed across the ends of same with a web 99 defining an opening 100 of polygonal configuration to receive a shoulder 102 of the respective fastener elements 68 in complementary relation thereto for holding the respective element 68 against rotation relative to the pan 56. The elements 68 each include a headed end 104 that includes the shoulder I02 and radial flange 106 which seats against the respective webs 99 of the seat pan to preclude passage of the fastener element 68 through the seat pan under the action of the fastener screws 72. The fastener elements 68 each define a tubular shank portion 108 that is suitably internally threaded for threaded co-operation with fastener screws 72.

The seat pan 56, as already mentioned, is formed to define the circumambient downwardly directed rim portion 74 terminating in rim 64 under which the edges of the fabric 60 are applied, and to which they are stapled as at 66. As indicated in FIG. 4, the shaping of the rim portion 74 is such that space 76 is formed, when the seat pan 56 is clamped against the shell seat portion l4, that accommodates any gathering of the fabric 60 edging that may be involved in applying the fabric to the seat pan.

The padding 58 is shown to be of one piece construc tion, but this is for illustrative purposes only, as it may also be several layers of padding material cut and superposed to provide the equivalent of padding 58. The shaping of the seat subassembly 26, as seen from FIG. 3, is such that it substantially fills the space defined by the shell surface portion 25 and presents the exterior appearance indicated in FlG. I.

The seat plate 56 is formed with breather openings 110 that are aligned with the breather openings 84 of the shell seat portion.

Referring now to FIGS. 9 and 10, in accordance with this invention, the fastener elements 68 are secured against movement upwardly of seat pan 56 by the application thereto of push nuts1l2. The push nuts 112 are a commercially available lock device comprising a disc like element 114 defining an annular flange 116 having integral therewith a plurality of angled teeth 118 disposed in aligned frustoconical relation which, when the push nut 1 12 is pressed onto the fastener element 68 to bring the flange 114 against the undersurface 109 of the seat pan 56, oppose movement of the fastener element 68 upwardly of the seat pan. The push nuts 112 are proportioned relative to the outer diameter of the fastener shank 108 such that prongs 118 bear firmly against the shank 108 in biting relation thereto on being applied thereto in the manner indicated in FIG. 9.

It will thus be seen that the fastener elements 68 are fixed to the seat pan 56 against movement upwardly or downwardly of the seat pan, and against rotative movement relative thereto. Shoulders 102 and pan openings 100 are of square configuration in the illustrated embodiment, but obviously other polygonal configurations may be employed.

The chair iron 30 illustrated is of the type that defines on either side of same a pair of ears 120 having openings to receive the respective fastener screws 72. Fastener screws 72 are conveniently of the washer head type for load spreading purposes. Likewise the flanges 106 of fastener elements 68 are proportioned for adequate load spreading purposes.

It will thus be seen that the fastener elements 68 are made a fixed part of the seat subassembly 26, and that when the seat subassembly and chair iron are assembled to the shell seat portion 14 in the manner indicated in FIG. 3, and the screws 72 are turned within the fastener elements 68, the planar webs 99 of the respective seat pan indentations 96 and 98 are drawn against the compression inserts 48 to apply the basic compressive forces involved against the compression resisting structure represented by the inserts 48 and seat board 28. This avoids application of compression stress concentrations to the material forming the shell 14.

It will also be observed that the seat subassembly 26 is readily removable from the chair, by merely removing the fastener screws 72. On removal of the seat subassembly, the fastening of the fabric material 60 to the seat pan 56 is readily exposed for removal and replacement of the fabric material 60 if so desired. This facilitates replacement of the seat subassembly fabric material in the field when so desired.

It will be observed that the fastener devices 54 are arranged so that the tension applied to sleeves 108 by the application thereof of fastener screws 72 does not tend to loosen the fastener device relative to the seat pad. Thus, the sleeve 68 is free of axial indenting or the like that would tend to straighten out under tension forces applied thereto and result in loosening of the fastener relative to the seat plate. The push nuts 112, in being pressed firmly against the seat pan under conditions which result in the fastener sleeve head flange 106 being disposed firmly against the upwardly facing surface 75 of the pan, (as defined by webs 99) firmly mold the fastener sleeves in place during use due to the action of the push nut lock teeth 118.

The foregoing description and the drawings are given merely to explain and illustrate the invention and the invention is not to be limited thereto, except insofar as the appended claims are so limited, since those skilled in the art who have the disclosure before them will be able to make modifications and variations therein withv out departing from the scope of the invention.

We claim:

1. A shell chair comprising:

a molded shell defining seat and back portions,

said seat portion having molded in same a generally planar reinforcing seat board that is exposed on the underside of said seat portion and underlies the upper side of said seat portion,

said seat portion including said seat board bcin formed with a plurality of fastener receiving openings extending therethrough,

a seat pan seated on the upper surface of said seat portion and having cushion padding applied thereto, on the upwardly facing side thereof,

a headed tubular fastener element disposed in each of said openings and carried by said pan, with the respective fastener elements having their headed ends disposed in engagement with said surface of said seat pan,

said fastener elements being made fast to said seat pan, 1

a chair base including a seat attachment member defining a plurality of screw receiving openings aligned with said seat portion openings,

and a screw received in each of said screw receiving openings,

said seat board and said seat pan at each of said seat portion openings having a compression resisting insert interposed therebetween through which the respective seat portion openings extend,

said screws being turned to clamp the respective inserts between said seat pan andsaid seat attachment member to make said seat pan fast to said seat portion.

2. A shell chair comprising:

a molded shell defining seat and backportions,

said seat portion having molded in same a generally planar reinforcing seat board that is exposed on the underside of said seat portion and underlies the upper side of said seat portion,

said seat portion including said seat board being formed with a plurality of fastener receiving openings extending therethrough,

a seat pan seated on the upper surface of said seat portion and having cushion padding applied thereto, on the upwardly facing side thereof,

a headed tubular fastener element disposed in each of said openings, with the respective fastener elements defining an internally threaded shank at one end of same and flanged head at their otherends,

said fastener elements having their ends disposed in engagement with'said surface of said seat pan,

means for making said fastener elements fast to said seat pan with said headed ends thereof engaging said pan surface,

said fastener shanks projecting into said openings, re-

spectively,

a chair base including a seat attachment member defining a plurality of screw receiving openings aligned with said seat portion openings,

and a screw received in each of said screw receiving openings and into threaded relation with the fastener shank disposed therein,

said seat board and said seat pan at each of said seat portion openings having a compression resisting insert interposed therebetween through which the respective seat portion openings extend,

said screws being turned to clamp the respective inserts between said seat pan and said seat attachment member to make said seat pan fast to said seat portion.

3. The shell chair set forth in claim 2, wherein:

said pan defines a downwardly angled marginal flange,

said cushion padding being covered by fabric material extending over said padding and under said pan thereabout,

said fabric material being stapled to said pan on the underside of same about said marginal flange thereof,

said screws clamping said pan marginal flange against said seat portion to clamp said fabric material therebetween,

said marginal flange defining with said seat portion a recess to receive bunched edge portions of said fabric. material.

4. The shell chair set forth in claim 2, wherein:

said means for making said fastener elements fast to said pan comprises a push nut for each fastener shank and pressed against the underside of said pan about the respective fastener shanks,

with said fastener element heads each defining a polygonal shoulder thereabout that is received in a complementary polygonal recess formed in said pan.

5. The shell chair set forth in claim 2, wherein:

said seat portion has a tack strip embedded therein about the sides and back thereof,

with the exposed surfaces of said shell being covered with padding and fabric material stapled to said tack strip and said seat board,

and a cover panel overlying said seat board and interposed between same and said seat attachment member,

said cover panel overlying the marginal edges of the fabric material that are stapled to said seat board,

6. The shell chair set forth in claim 2, wherein: said fastener shanks are free of indenting axially thereof. 

1. A shell chair comprising: a molded shell defining seat and back portions, said seat portion having molded in same a generally planar reinforcing seat board that is exposed on the underside of said seat portion and underlies the upper side of said seat portion, said seat portion including said seat board being formed with a plurality of fastener receiving openings extending therethrough, a seat pan seated on the upper surface of said seat portion and having cushion padding applied thereto, on the upwardly facing side thereof, a headed tubular fastener element disposed in each of said openings and carried by said pan, with the respective fastener elements having their headed ends disposed in engagement with said surface of said seat pan, said fastener elements being made fast to said seat pan, a chair base including a seat attachment member defining a plurality of screw receiving openings aligned with said seat portion openings, and a screw received in each of said screw receiving openings, said seat board and said seat pan at each of said seat portion openings having a compression resisting insert interposed therebetween through which the respective seat portion openings extend, said screws being turned to clamp tHe respective inserts between said seat pan and said seat attachment member to make said seat pan fast to said seat portion.
 2. A shell chair comprising: a molded shell defining seat and back portions, said seat portion having molded in same a generally planar reinforcing seat board that is exposed on the underside of said seat portion and underlies the upper side of said seat portion, said seat portion including said seat board being formed with a plurality of fastener receiving openings extending therethrough, a seat pan seated on the upper surface of said seat portion and having cushion padding applied thereto, on the upwardly facing side thereof, a headed tubular fastener element disposed in each of said openings, with the respective fastener elements defining an internally threaded shank at one end of same and flanged head at their other ends, said fastener elements having their ends disposed in engagement with said surface of said seat pan, means for making said fastener elements fast to said seat pan with said headed ends thereof engaging said pan surface, said fastener shanks projecting into said openings, respectively, a chair base including a seat attachment member defining a plurality of screw receiving openings aligned with said seat portion openings, and a screw received in each of said screw receiving openings and into threaded relation with the fastener shank disposed therein, said seat board and said seat pan at each of said seat portion openings having a compression resisting insert interposed therebetween through which the respective seat portion openings extend, said screws being turned to clamp the respective inserts between said seat pan and said seat attachment member to make said seat pan fast to said seat portion.
 3. The shell chair set forth in claim 2, wherein: said pan defines a downwardly angled marginal flange, said cushion padding being covered by fabric material extending over said padding and under said pan thereabout, said fabric material being stapled to said pan on the underside of same about said marginal flange thereof, said screws clamping said pan marginal flange against said seat portion to clamp said fabric material therebetween, said marginal flange defining with said seat portion a recess to receive bunched edge portions of said fabric material.
 4. The shell chair set forth in claim 2, wherein: said means for making said fastener elements fast to said pan comprises a push nut for each fastener shank and pressed against the underside of said pan about the respective fastener shanks, with said fastener element heads each defining a polygonal shoulder thereabout that is received in a complementary polygonal recess formed in said pan.
 5. The shell chair set forth in claim 2, wherein: said seat portion has a tack strip embedded therein about the sides and back thereof, with the exposed surfaces of said shell being covered with padding and fabric material stapled to said tack strip and said seat board, and a cover panel overlying said seat board and interposed between same and said seat attachment member, said cover panel overlying the marginal edges of the fabric material that are stapled to said seat board.
 6. The shell chair set forth in claim 2, wherein: said fastener shanks are free of indenting axially thereof. 